Triboelectric energy harvesting devices are elements for converting mechanical energy into useful electric energy by using an electrostatic induction phenomenon due to a frictional contact. Tribo-electricity is generated when materials having electron affinity different from each other are brought into contact through friction. Typical triboelectric energy harvesting devices mostly operate under vertically acting friction force and are realized on a hard surface such as silicon or glass, or on a flexible surface such as a PET or kapton film. Such typical triboelectric energy harvesting devices exhibit low electric power efficiency with respect to an extending deformation and have problems in that the frequency of vibration applied to the devices is variously changed and effectiveness of the devices may not be ensured under an environment in which the direction and the strength of the deformation are not constant. In addition, typical triboelectric energy harvesting devices have low wearability and thus are not suitable to charge wearable electronic devices.